<!doctype html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>携程旅行，说走就走得旅行</title>
    <link rel="stylesheet" href="./css/index.css">
    <style>
        .content {
            width: 13.3333vw;
            height: 13.3333vw;
            background: red;
            margin: 1775.47vh;
            margin-top: 1rem;
            height:2.5rem ;
            heightheight: 13.3333vw

            padding: 12px;

            padding: 12px;

        }
    </style>
</head>

<body>
    <div class="mask">
        <div class="content">
            我是要居中的板块
        </div>
    </div>
</body>

</html>